Required Number of Events Given Hazard Ratio — getNeventsFromHazardRatio • lrstat

Obtains the required number of events given the hazard ratios under the null and alternative hypotheses for a group sequential design.

Usage

getNeventsFromHazardRatio(
  beta = 0.2,
  kMax = 1L,
  informationRates = NA_real_,
  efficacyStopping = NA_integer_,
  futilityStopping = NA_integer_,
  criticalValues = NA_real_,
  alpha = 0.025,
  typeAlphaSpending = "sfOF",
  parameterAlphaSpending = NA_real_,
  userAlphaSpending = NA_real_,
  futilityBounds = NA_real_,
  typeBetaSpending = "none",
  parameterBetaSpending = NA_real_,
  userBetaSpending = NA_real_,
  spendingTime = NA_real_,
  hazardRatioH0 = 1,
  hazardRatio = NA_real_,
  allocationRatioPlanned = 1,
  rounding = 1L
)

Arguments

beta: Type II error. Defaults to 0.2.
kMax: The maximum number of stages.
informationRates: The information rates in terms of number of events. Fixed prior to the trial. Defaults to (1:kMax) / kMax if left unspecified.
efficacyStopping: Indicators of whether efficacy stopping is allowed at each stage. Defaults to TRUE if left unspecified.
futilityStopping: Indicators of whether futility stopping is allowed at each stage. Defaults to TRUE if left unspecified.
criticalValues: Upper boundaries on the z-test statistic scale for stopping for efficacy.
alpha: The significance level. Defaults to 0.025.
typeAlphaSpending: The type of alpha spending. One of the following: "OF" for O'Brien-Fleming boundaries, "P" for Pocock boundaries, "WT" for Wang & Tsiatis boundaries, "sfOF" for O'Brien-Fleming type spending function, "sfP" for Pocock type spending function, "sfKD" for Kim & DeMets spending function, "sfHSD" for Hwang, Shi & DeCani spending function, "user" for user defined spending, and "none" for no early efficacy stopping. Defaults to "sfOF".
parameterAlphaSpending: The parameter value for the alpha spending. Corresponds to \(\Delta\) for "WT", \(\rho\) for "sfKD", and \(\gamma\) for "sfHSD".
userAlphaSpending: The user defined alpha spending. Cumulative alpha spent up to each stage.
futilityBounds: Lower boundaries on the z-test statistic scale for stopping for futility at stages 1, ..., kMax-1. Defaults to rep(-6, kMax-1) if left unspecified. The futility bounds are non-binding for the calculation of critical values.
typeBetaSpending: The type of beta spending. One of the following: "sfOF" for O'Brien-Fleming type spending function, "sfP" for Pocock type spending function, "sfKD" for Kim & DeMets spending function, "sfHSD" for Hwang, Shi & DeCani spending function, "user" for user defined spending, and "none" for no early futility stopping. Defaults to "none".
parameterBetaSpending: The parameter value for the beta spending. Corresponds to \(\rho\) for "sfKD", and \(\gamma\) for "sfHSD".
userBetaSpending: The user defined beta spending. Cumulative beta spent up to each stage.
spendingTime: A vector of length kMax for the error spending time at each analysis. Defaults to missing, in which case, it is the same as informationRates.
hazardRatioH0: Hazard ratio under the null hypothesis for the active treatment versus control. Defaults to 1 for superiority test.
hazardRatio: Hazard ratio under the alternative hypothesis for the active treatment versus control.
allocationRatioPlanned: Allocation ratio for the active treatment versus control. Defaults to 1 for equal randomization.
rounding: Whether to round up the number of events. Defaults to 1 for rounding.

Value

The required number of events.

Author

Kaifeng Lu, kaifenglu@gmail.com

Examples


getNeventsFromHazardRatio(
  beta = 0.2, kMax = 2,
  informationRates = c(0.5,1),
  alpha = 0.025, typeAlphaSpending = "sfOF",
  typeBetaSpending = "sfP",
  hazardRatio = 0.673)
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